If you live in a large city, you can probably count the number of stars that you are able to see in the night sky with the fingers of one hand.
Here in Toronto, I am able to look out my windows and see no more than five stars, and one or two of those are more than likely aeroplanes.
A shocking 80% of the North American population is unable to admire the beauty of a night sky. In Europe, 60% of the population live under starless skies.
The stars have not disappeared. The cosmos has not drifted away into some black hole. Rather, it's the overwhelming light pollution of our cities that blanks out the darkness to such an extent that we no longer have a visual connection to the stars.
Where I live, it is never dark. Street lighting overwhelms everything with an eerie yellow glow. The proponents of such extreme lighting cite crime and public safety on the roads as the primary reason for a well-lit city. Stars hardly matter when judged against robbery, rape, and traffic collisions. Safety supersedes celestial contemplation.
I suspect there is more to our loss of a starry night than most realise. The blanket of light that eliminates the darkness of night has been found to be detrimental to human health, as well as the health of our animal population. Constant light interferes with our circadian rhythm, a roughly 24 hour cycle in the physiological processes of living beings, including plants, animals, fungi and bacteria. Circadian rhythms are important in determining the sleeping and feeding patterns of all animals, including human beings. There are clear patterns of brain wave activity, hormone production, cell regeneration and other biological activities linked to this daily cycle, and studies have found that a disrupted circadian rhythm can lead to increased cases of cardiovascular events, obesity, and even breast cancer.
The effect of constant light is not limited to physical well-being. Psychological studies have shown that a disruption of the normal shift from light to dark can lead to sleep disorders, and neurological problems like depression and bipolar disorder.
We need the night. We need the stars. We need to be able to look up and ponder the vastness of space. Even though it may feel like a lost cause, every star we bring back to the city makes a difference, and it can be done - and indeed, has been done - through more thoughtfully designed urban lighting. Though we might love the light, and feel safe under its undaunting glow, we also need the dark.
